Detectives arrested a 12-year-old girl and her 10-year-old sister for allegedly abducting their neighbour's one-year-old son and demanding $200,000 (£100,000) for his return.

Brandon Wells was safe and well on Thursday night, hours after intruders broke into his home and took him while his mother, Sheila Wells, slept, police said. "I've been doing this 18½ years, and this is the first time I know of when a 10- and a 12-year-old kidnapped a one-year-old," police captain Dean Grassino said.

The siblings, who were not named, are accused of sneaking into Ms Wells' home in Enid, Oklahoma, taking Brandon and leaving a ransom note. "If you want to see your son again then you won't call police and report him missing and you will leave $200,000 on the sofa tonight and we will return your son back safe," the note read, according to police. It was signed "the kidnappers".

The plan began to unravel when the girls' mother saw them with the boy, police said. They told their mother they had found him on the corner, police said.

As the girls' mother tried to find Ms Wells' telephone number, the 12-year-old returned to Brandon's home and told his mother that it was the younger sister who was responsible for the abduction, Capt Grassino said. Ms Wells immediately collected her son and the police were called.

Ms Wells said she had banned the 10-year-old girl from her home a few weeks earlier, but did not say why.

The girls appeared in Garfield county district court on Thursday afternoon and were taken to a centre for juveniles. They have not been formally charged.

"I know they're so young, but they need to learn from their mistakes," Ms Wells said.